FFCs have superior utility and operability because they arrange multiple leads densely and are very flexible; consequently, they are widely used in small electronic devices such as CD players, video cameras, and small business (office) devices such as copiers and fax machines.
Japanese Utility Model 3-22869 and Japanese Patent Application 59-23482, for example, disclose conventional connectors for FFCs. Such conventional FFC connectors generally include hook-shaped contacts or a single beam-shaped contact and the FFC end is overlapped with a slider's insulated tongue inside an insulated housing and is thereby connected and secured.
However, such conventional FFC connectors inevitably are large due to the contact shape and use of a slider, so that it is impossible or extremely difficult for them to meet the demand for miniaturization in the latest electronic devices. Also, it is difficult for such conventional FFC connectors to adequately handle multiple contacts if there are about 40 contacts, for example. Furthermore, it is hard to do an electrical continuity check on whether or not the FFC leads touching correctly.
Therefore, with the intention of resolving the above-noted defects of conventional FFC connectors, the object of this invention is to present a flat-cable connector that can easily be miniaturized and densely packed, that has superior operability, and provides ease of use for continuity testing.
Prior art FIGS. 9-10 show one conventional example of such an FFC connector 1. FIG. 9 is a top view, FIG. 10 is a cross-section along line B--B, and FIG. 11 shows the end of a commonly known FFC used in FFC connector 1.
Long thin cable insertion groove 3 is formed from the top towards the bottom of FFC connector 1's insulated housing 2, and multiple contact-receiving apertures 4a-4b are formed along cable insertion groove 3. Furthermore, key 5 is formed by, for example, unitary molding to cross cable insertion groove 3 at a position which is off-center relative to insulated housing 2's cable insertion groove 3. Additionally, as shown in FIG. 10, contacts 6 are pressed into each contact-receiving aperture 4a-4b from the bottom of insulated housing 2. Contact 6's single-beam contact arm 7 is inserted into aperture 4a. Holding arm 8 is inserted into aperture 4b, and soldering tine 9 extends downward from insulated housing 2's bottom to the outside insulated housing 2. Tine 9 is inserted into a hole in a circuit board (not shown) and connected by soldering, for example.
The FFC "C" used in conjunction with FFC connector 1 has multiple, flat, parallel leads W which are insulated from each other and are coated and adhered to a plastic base. Additionally, slit S, which has a predetermined width, is formed in the end of cable C to determine the insertion orientation into FFC connector 1's cable insertion groove 3. Slit S aligns with positioning key 5 in FFC connector 1's cable insertion groove 3, and cable C is then pushed into groove 3. Through this pushing, each exposed lead W at the end of FFC C makes electrical contact with contact point 7a formed near the tip of each contact 6's contact arm 7.
In such prior FFC connectors, it is difficult to arrange a large enough contact pressure for each contact between FFC C and FFC connector 1 due to FFC C's frictional properties. If the contact pressure is fairly large, the insertion force increases and it becomes difficult to insert FFC C into cable insertion groove 3. On the other hand, if the contact pressure is too small, the electrical contact becomes insecure and there is concern that FFC C could come out of FFC connector 1 with a comparatively small separation force. Therefore, an FFC connector is required which has a low insertion force along with an adequate extraction force so that FFC C is not extracted from FFC connector 1 even if a relatively large separation force is applied.
Therefore, in Japanese Utility Application 3-358045, for such an FFC connector this applicant previously proposed pushing in and securing a separate key plug, formed of an elastic plastic member, into a slot in the insulated housing instead of a bar unitarily molded at both ends to the insulated housing and crossing the cable insertion groove, so that the key plug engages with a non-linear slit formed in the end of the FFC. The key plug and FFC slit do not greatly increase the insertion force, and engagement of the slit's stepped unit increases the extraction force when it is desired to extract the FFC.
However, using a separate key plug in the insulated housing has the disadvantage of increasing the number of parts and the number of assembly processes, so that it results in a complicated design with high cost.